Roller double contact mechanism



Oct. 2o, 1931. Q R TOWNSEND 1,828,692

ROLLER DOUBLE CONTACT MECHANISM Filed Jan. 2, 1930 1m ULg/11 www@ 'i Inventor' George R-Towv1sev1d- BH Hts Aitor-merg Patented Oct. 2(1), 1931 N11-aoI s'rarlfasv PATENT ol-Fica GEORGE n. rowNsENn, or scnENEcrAnY, NEW Yoan, AssIGNoE rro GENERAL ELEC- 'raro comm, n conroaarron 'or NEW Yoax ROLLER DOUBLE CONTACT HECHANISM Application tiled January 2, 1930. Serial No. 417,923.

ditions.

'' In oil burner control systems a switching means responsive to flame conditions is usually employed in the fire-box of the furnace. One function of such a switch is to establish proper circuit connections for starting the electrical oil burner `equipment when the switch is cool and to establish different circuit connections after flame is obtained.

In this way the switch automatically prevents the starting of the electrical oil burner equipment under impro r vand dangerous conditions so as'to avoi any accumulation of oil and oil vapors in a hot^iirebox with possibilities of a dangerousY explosion.

Thus the principal object of my invention is to provide an improved automatic switching means operable between tw o circuit controlling posltions and responsive with precision and certainty to ilame conditions.

A further object of my invention is to provide a iiame-responsive switch with a roller contact so that one circuit will be made before another is broken.

' My invention will be better understood by reference to the drawin which show the preferred embodiment o my invention.

Fig. 1 represents the preferred embodiment of the switch mechanism with the cover removed therefrom.

Fig, 2 is a detail showing of the iameres onsive element.

ig. 3 is a 5 detail showing of the' switchI mechanism.

Fig. 4 shows the device embodied in a furond contact will be engaged by the movable part before the first contact is disengaged therefrom. In this manner the second circuit maybe completed before the first circuit is broken.

Referring to the drawing Fig. 1, the numeral 1 designates a base upon `whlch is mounted a support 2. The support 2 has mounted thereon the contact plates 3, 4 and 5 which are engaged by means of the roller contact 6 mounted in thesupporting frame 7.

The supporting frame 7 by means of spring 8 is biased to cause roller 6 to contact with the contact plates. This frame 7 is mounted upon a lever y9 which is -pivoted in the frame 10 mounted upon the base l. A second biasing spring 11 engages the lever 9. A lever mechanism consisting of parts 13 and 14 engages the lever 9 by means of a ivotal sliding connection l2. Parts 13 an 14 are fric'- tionally engaged at 15 which permits relative movement between the parts 13 and 14 should circumstances require such a movement if the roller contact 6 is in either of the pivot# ing positions and further movement of the member 14 results from the operation of the iame-responsive device. The member 14 is pivotally mounted in the support 17. A flame-responsive device, the casing of which'extends from the rear of the base 1, is connected to the lever 14 by means of the element 18 which forms an extension of the y part 19 extending from the casing 20.

18. Movement of part 19 is-magniiied at the roller Contact by means of the multiplying feature of the levers.

Referrin to Fig. 2, the casing 20 which is made o nichrome has mounted therein the quartz rod 21 which supports the extension member 19. The nichrome casing and the quartz rod have different coeilicientsof expansion which results in the movement of the quartz rod 21 with respect to the base 1 upon which the casing 20 is mounted in response to flame conditions.

Fig. 3 is a detailed showing of the switch mechanism. The contact plates 4 and 5 are carried on the opposite side of the su port 2 from the contact plate 3. It will be o served that the roller Contact 6 is at all times in en- 10 gagement with the contact plate 3 and at the limit of its travel with either the contact plates 4 and 5. rIhe spring 8 biases the frame member 7 which is pivoted in the lever 9 and causes the roller contact 6 to have engagement with the contact plates at allctimes.

Referring to Fig. 4 a furnace is designated by the numeral 30 in the re box of which is mounted the flame-responsive device 20 mounted on the base 1 which is attached to the rear of the frame.

The operation of the device is as follows: In Fig. 1 it will be seen that the roller contact is in one position with the roller in engagement with the plates Sand 4. With the casing 20 extending into the fire-box of the furnace upon a ilame being established therein the casing 20 and the quartz rod 21 therein will expand in response to the heat absorbed from the flame. Because of the difference of coefcient of expansion of the casing 2O andV the quartz rod 21, the casing 20 will expand to a greater extent than the rod 2l. Since the casing 20 is firmly attached to the basel the end of the casing to which the quartz rod 21 is attached will move to the left, 4as shown in Fig. 2. This will cause the element 18to draw the lever 14 in a clockwise direction about the pivot in the support 17. By means of the pivotal connection 12, the lever 9 will be rotated about its pivot in the frame 10 in a counter-clockwise direction, thus causing the roller 6 to move from contact with the contact plate 4 to a position in contact with the plate 5. It will be noticed, however, that since the roller 6 has a greater diameter than the difference between the contact plates 4 and 5 that the roller 6 will engage the contact plate 5 before it disengages the contact plate 4. Thus, before one circuit is deenergized, another circuit will be energized. It will be understood, ofcourse, that the plates 4, 5, and 3 are connected with conductors which lead to circuits to be controlled by the 'switch mechanism.

If the flame goes out for any reason, the

' casing 20 `will cool, thereby permitting the quartz rod 21 tb move to the right, thus causing the lever mechanism to move in opposite direction to cause the roller 6 to again move to its initial position in which the plates 3 and 4 were originally engaged.

It will thus be seen that I have provided a switch mechanism which is responsive to ame conditions and in which one circuit is not broken until another circuit is completed.

The embodiment of the invention illus trated and described herein has been selected for the purpose of clearly setting forth the principles involved. It will be apparent however, that the invention is susceptible oli being modified to meet the different conditions encountered in its use, and I, vtherefore, aim to cover by the appended claims different of said stationary contacts and an element responsive to flame conditions connected to said relatively movable members causing movement of the same to move said movable circuit controlling roller contact in response yto flame conditions.

2. VIn a dame-responsive control switch, a.' switch mechanism comprising a plurality of,

stationary contacts, two ofsaid contacts being oppositely -disposed to a third, and a roller contact cooperating therewith, said roller engaging said third contact at all times, lever mechanism having a multiplying movement connected to said roller Contact to actuate the same and a flame-responsive device connected to said lever mechanism for causing movement of the said lever mechanism in response to flame conditions.' 3. In a heat-responsive circuit controlling device, a plurality of stationary contacts, two of said contacts oppositely disposed to a third a movable roller contact element for alwa engaging said third contact and one of said two contacts and movable to engage the other of said two contacts while remaining in engagement with the third contact, said roller,

engaging the other of said two contacts before disengaging said first of two contacts in moving from the first to the other of said two contacts, and. a heat-responsive means connected to said roller contact for causing movement thereof to contact with one or the other ofA said two contacts and said third contact.

4. A flame-responsive control switch, aplurality of. stationary contacts, a roller contact cooperating therewith and4 continuously biased. to engage withv at least two of said stationary contacts, said roller contactbeing y movable between limits to en age different contacts, a plurality of pivoted evers connected to said roller contact havinga ,lost motion link connection to permit movement of said.

levers with respect to eachA other'when said roller contact isat the limit of. its travel andAA a flame-responsive element connectedto saidA levers for moving the same to cause sald roll.-

`er contact to move between its limits-in ref spense to flame/conditions.

5. In a lame-responsive switch device, af

lll

tacts, a dame-responsive element consisting of two materials with different coeicients o expansion and levers connected to one of said materials/and said roller contact wherebythe difference of ex ansion in said materials upon heating thereo will cause said roller contact to move from engagement with one of said two stationary contacts to enga another of f said two stationary contacts, said roller con- 4stationary contact tact at all times engaging said third stationary contact and being in contact at all times with a plurality of said contacts.

6. In a flame-responsive control device, a switch mechanism comprising a plurality of lates, two of said lates oppositely disposedj spaced from each other, and a roller contact cooperating with said contactfplates being a1- Ways in contact with said thir plate and normally with one or the other of said two plates, a pivoted frame supporting said roller contact and biased to cause said roller to Contact with said plates, a biased lever pivotally mounted supporting said frame, a second lever mechanlsm pivotally mounted and having a pin and slot connection with said first lever, said levers forming a movement multiplying system for said roller contact, a support for pivotally supporting said second lever, va Haine-responsive device adjacent said support and engaging said second lever to move the same when said Haine-responsive device expands and contracts in response to flame conditions, said levers causing movement of said roller contact from one of said two contact plates to the other of said two contact plates in response to said lever movement.

In witness whereof, I have hereunto set my hand this 31st day of December, 1929.

- GEORGE R. TOWNSEND.

to a third and slightly- 

